2025-10-30 14:06 UTC-0700 ~ Harshit Mogalapalli harshit.m.mogalapalli@oracle.com
It is useful to print map ID on successful creation.
JSON case: $ ./bpftool -j map create /sys/fs/bpf/test_map4 type hash key 4 value 8 entries 128 name map4 {"id":12}
Generic case: $ ./bpftool map create /sys/fs/bpf/test_map5 type hash key 4 value 8 entries 128 name map5 Map successfully created with ID: 15
Bpftool Issue: https://github.com/libbpf/bpftool/issues/121 Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com
tools/bpf/bpftool/map.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index c9de44a45778..80c96b33b553 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -1251,6 +1251,8 @@ static int do_create(int argc, char **argv) LIBBPF_OPTS(bpf_map_create_opts, attr); enum bpf_map_type map_type = BPF_MAP_TYPE_UNSPEC; __u32 key_size = 0, value_size = 0, max_entries = 0;
- struct bpf_map_info map_info = {};
- __u32 map_info_len = sizeof(map_info); const char *map_name = NULL; const char *pinfile; int err = -1, fd;
@@ -1353,13 +1355,24 @@ static int do_create(int argc, char **argv) } err = do_pin_fd(fd, pinfile);
- close(fd); if (err)
goto exit;
goto close_fd;
- if (json_output)
jsonw_null(json_wtr);
- err = bpf_obj_get_info_by_fd(fd, &map_info, &map_info_len);
- if (err) {
p_err("Failed to fetch map info: %s\n", strerror(errno));
Nit: Please remove the line break ('\n') here, p_err() already adds it.
goto close_fd;- }
- if (json_output) {
jsonw_start_object(json_wtr);jsonw_int_field(json_wtr, "id", map_info.id);jsonw_end_object(json_wtr);
I've been wondering if we should have some parent object like '{"map_created": { "id": 15 }}' in case we later add more output, but I can't really see a good use case at the moment, I'm probably overthinking it... So I'm good with the current output. Thanks for this!
With the line break removed:
Reviewed-by: Quentin Monnet qmo@kernel.org